I just noticed something while remembering how Diamond Tiara was talking about how Applebloom having two cutie marks was fake, but I wasn't sure what it was. So I started searching on YouTube and finally found it!

They are not? Okay, I will believe that they aren't if you can explain something to me: How exactly are a Quill and a Sofa related to each other for them to be considered a single cutie mark and not two separate ones. Because I really can't see it... sorry.